Antacid

[3] Antacids are available over the counter and are taken by mouth to quickly relieve occasional heartburn, the major symptom of gastroesophageal reflux disease and indigestion.

[6] Conventional effervescent tablets contain a significant amount of sodium and are associated with increased odds of adverse cardiovascular events according to a 2013 study.

[7] Alternative sodium-free formulations containing magnesium salts may cause diarrhea, whereas those containing calcium or aluminum may cause constipation.

[9] In vitro studies have found a potential for acid rebound to occur due to antacid overuse, however the significance of this finding has been called into question.

[2][13] Antacids do not directly inhibit acid secretion, and thus are distinct from acid-reducing drugs like H2-receptor antagonists or proton pump inhibitors.

[19] Chewable tablets are one of the most common forms of antacids, most frequently made from carbonate or hydroxide salts, and are readily available over the counter.

[8]: Figure 1  Common carbonate salts available in tablet form include those of calcium, magnesium, aluminum, and sodium.

[21][22][23] Common ingredients include citric acid and sodium bicarbonate, which react when in contact with water to produce carbon dioxide.